This disclosure relates to a support unit, an apparatus and a method for treating a substrate.
Plasma is generated by very high temperature, strong electric fields, or RF electromagnetic fields, and refers to a state of ionized gas composed of ions, electrons, radicals, and the like. The semiconductor device manufacturing process performs an etching process using plasma. The etching process performed by colliding the ion particles contained in the plasma with the substrate. The etching process is performed inside the process chamber. A process gas is supplied into the process chamber, and high-frequency power is applied to the process chamber to excite the process gas into a plasma state.
FIG. 1 shows a general support unit in a substrate treating apparatus. A first dielectric plate 1 for supporting a substrate W, an electrode layer 2 of a conductive material in a bottom part, and a second dielectric plate 3 are sequentially provided. The first dielectric plate 1 may be provided with a lift pin (not shown) for supporting the substrate. A cooling path 4 where a cooling fluid flows is formed in the second dielectric plate 3. When the cooling fluid flows, electrostatic force is generated by the friction between the cooling fluid and the outer wall of the cooling path. Charges on the outer wall of the cooling path 4 cause electromagnetic induction phenomena to occur on the electric charges existing in the electrode layer and the plates 1, 2, 3. For example, referring to FIG. 1, Positive charges are distributed in the upper portion of the second dielectric plate 3 due to negative charges generated in the outer wall of the cooling path. Also, a negative charge is distributed in the lower part of the electrode layer 2, and a positive charge is distributed in the upper part of the electrode layer 2. Also, due to the electromagnetic induction phenomenon, negative charges are distributed in the lower portion of the first dielectric plate 1, and positive charges are distributed in the upper portion of the first dielectric plate 1. A negative charge is distributed to a lower portion of the substrate made of a silicon material, and as a result, the substrate is chucked to the first dielectric plate 1.
On the other hand, when the process is finished and the substrate is to be unloaded from the first dielectric plate 1, the substrate w must not be chucked to the first dielectric plate 1. However, as described above, there is a problem that the substrate is chucked by an unintended chucking force by electromagnetic induction, and the substrate is damaged in the process of unloading the substrate.